Effects of tongue cleaning on bacterial flora in tongue coating and dental plaque: a crossover study

Abstract

BackgroundThe effects of tongue cleaning on reconstruction of bacterial flora in dental plaque and tongue coating itself are obscure. We assessed changes in the amounts of total bacteria as well as Fusobacterium nucleatum in tongue coating and dental plaque specimens obtained with and without tongue cleaning.MethodsWe conducted a randomized examiner-blind crossover study using 30 volunteers (average 23.7 ± 3.2 years old) without periodontitis. After dividing randomly into 2 groups, 1 group was instructed to clean the tongue, while the other did not. On days 1 (baseline), 3, and 10, tongue coating and dental plaque samples were collected after recording tongue coating score (Winkel tongue coating index: WTCI). After a washout period of 3 weeks, the same examinations were performed with the subjects allocated to the alternate group. Genomic DNA was purified from the samples and applied to SYBR® Green-based real-time PCR to quantify the amounts of total bacteria and F. nucleatum.ResultsAfter 3 days, the WTCI score recovered to baseline, though the amount of total bacteria in tongue coating was significantly lower as compared to the baseline. In plaque samples, the bacterial amounts on day 3 and 10 were significantly lower than the baseline with and without tongue cleaning. Principal component analysis showed that variations of bacterial amounts in the tongue coating and dental plaque samples were independent from each other. Furthermore, we found a strong association between amounts of total bacteria and F. nucleatum in specimens both.ConclusionsTongue cleaning reduced the amount of bacteria in tongue coating. However, the cleaning had no obvious contribution to inhibit dental plaque formation. Furthermore, recovery of the total bacterial amount induced an increase in F. nucleatum in both tongue coating and dental plaque. Thus, it is recommended that tongue cleaning and tooth brushing should both be performed for promoting oral health.

Does the Prevalence of Periodontal Pathogens Change in Elderly Edentulous Patients after Complete Denture Treatment?

“…Patients who participated in the study were thoroughly instructed how to properly clean and store dentures, and were monitored by professionals. Several studies have found that the dorsum of the tongue can act as a reservoir of harmful pathogens and a source of infection, but cleaning of the tongue alone, while reducing the amount of bacteria in the tongue coating, does not contribute to the inhibition of dental plaque formation . To improve oral hygiene and reduce the presence of periodontal pathogens, immersion in alkaline peroxide and ultrasonic vibration can be used as auxiliary agents for cleaning complete dentures …”

Effects of lactoferrin and lactoperoxidase‐containing food on the oral hygiene status of older individuals: A randomized, double blinded, placebo‐controlled clinical trial

“…The tongue coating score was significantly improved at 4 and 8 weeks in both groups. The tongue coating comprises oral microorganisms, and pathogenic bacteria reside beneath the epithelium and salivary components . It is removed in part by abrasion and autopurification of the tongue surface by food.…”

“…The tongue coating comprises oral microorganisms, and pathogenic bacteria reside beneath the epithelium and salivary components. 30…”

Induction and inhibition of oral malodor

“…Bordas et al () found that mechanical tongue cleaning for 3 days with or without chemical intervention significantly reduced the number of bacteria on the tongue and in the tongue coating. Matsui et al () reported that the number of total bacteria on the tongue was significantly lower than the baseline after 3 days of tongue cleaning, while the level of tongue coating returned to the baseline. On the other hand, the trial conducted by Quirynen et al () showed that 2 weeks of tongue cleaning reduced the numbers of bacteria on the tongue, but without reaching statistical significance, while the amount of tongue coating was significantly reduced.…”

“…Tongue cleaning combined with periodontal treatment improves oral malodor in patients with periodontitis, whereas tongue cleaning is more effective at reducing oral malodor than periodontal treatment in patients with gingivitis (Pham et al, ). Tongue cleaning reduces bacterial numbers (Bordas et al, ; Matsui et al, ) and substrates for putrefaction (Bordas et al, ; Quirynen et al, ), but the effects are transient. Bordas et al () found that mechanical tongue cleaning for 3 days with or without chemical intervention significantly reduced the number of bacteria on the tongue and in the tongue coating.…”